* pathnames.sgml: Try to be more clear explain raw devices.

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Corinna Vinschen 2009-03-09 10:23:44 +00:00
parent 313fb10ba2
commit f9f478ad80
2 changed files with 61 additions and 22 deletions

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@ -1,3 +1,7 @@
2009-03-09 Corinna Vinschen <corinna@vinschen.de>
* pathnames.sgml: Try to be more clear explain raw devices.
2009-03-03 Corinna Vinschen <corinna@vinschen.de> 2009-03-03 Corinna Vinschen <corinna@vinschen.de>
* faq-using.xml: Rework UTF FAQ to accommodate latest setlocale * faq-using.xml: Rework UTF FAQ to accommodate latest setlocale

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@ -421,11 +421,13 @@ Read on for more information.</para>
directory as Cygwin automatically simulates it internally. directory as Cygwin automatically simulates it internally.
These devices cannot be seen with the command <command>ls /dev/</command> These devices cannot be seen with the command <command>ls /dev/</command>
although commands such as <command>ls /dev/tty</command> work fine. although commands such as <command>ls /dev/tty</command> work fine.
If you want to be able to see all devices in If you want to be able to see all well-known devices in
<filename>/dev/</filename>, you can use Igor Pechtchanski's <filename>/dev/</filename>, you can use Igor Pechtchanski's
<ulink <ulink
url="http://cygwin.com/ml/cygwin/2004-03/txt00028.txt">create_devices.sh</ulink> url="http://cygwin.com/ml/cygwin/2004-03/txt00028.txt">create_devices.sh</ulink>
script. script. This script does not add the raw disk devices, though. Again,
it's not necessary to see an existing device in /dev to access it. The script
is just for the fun of it.
</para> </para>
<para> <para>
@ -491,48 +493,81 @@ from the POSIX namespace to the internal NT namespace.
E.g. the first harddisk is the NT internal device \device\harddisk0\partition0 E.g. the first harddisk is the NT internal device \device\harddisk0\partition0
or the first partition on the third harddisk is \device\harddisk2\partition1. or the first partition on the third harddisk is \device\harddisk2\partition1.
The first floppy in the system is \device\floppy0, the first CD-ROM is The first floppy in the system is \device\floppy0, the first CD-ROM is
\device\cdrom0 and the first tape drive is \device\tape0. The mapping \device\cdrom0 and the first tape drive is \device\tape0.</para>
to the POSIX /dev namespace is as follows:
<para>The mapping from physical device to the name of the device in the
internal NT namespace can be found in various places. For hard disks and
CD/DVD drives the Windows "Disk management" (part of the "Computer Management"
console) shoes the mapping "Disk 0" is \device\harddisk0, "CD-ROM 2" is
\device\cdrom2. Another place to find this mapping is the "Device Management"
console. Disks have a "Location" number, tapes have a "Tape Symbolic Name",
etc. Unfortunately the places where to find this information is not very
well-defined.</para>
<para>
For external disks (USB-drives, CF-cards in a cardreader, etc) you can use
Cygwin to find out the mapping. <filename>/proc/partitions</filename>
contains a list of raw drives known to Cygwin. The <command>df</command>
command shows a list of drives and their respective sizes. If you match
the information between <filename>/proc/partitions</filename> and the
<command>df</command> output, you should be able to figure out which
external drive corresponds to which raw disk device name.</para>
<note><para>Apart from tape devices which are not block devices and are
by default accessed directly, accessing mass storage devices raw
is something you should only do if you know what you're doing and know how to
handle the information. <emphasis role='bold'>Writing</emphasis> to a raw
mass storage device you should only do if you
<emphasis role='bold'>really</emphasis> know what you're doing and are aware
of the fact that any mistake can destroy important information, for the
device, and for you. So, please, handle this ability with care.
<emphasis role='bold'>You have been warned.</emphasis></para></note>
<para>
Last but not least, the mapping from POSIX /dev namespace to internal
NT namespace is as follows:
</para> </para>
<screen> <screen>
/dev/st0 \device\tape0, rewind POSIX device name Internal NT device name
/dev/nst0 \device\tape0, no-rewind
/dev/st1 \device\tape1 /dev/st0 \device\tape0, rewind
/dev/nst1 \device\tape1 /dev/nst0 \device\tape0, no-rewind
/dev/st1 \device\tape1
/dev/nst1 \device\tape1
... ...
/dev/st15 /dev/st15
/dev/nst15 /dev/nst15
/dev/fd0 \device\floppy0 /dev/fd0 \device\floppy0
/dev/fd1 \device\floppy1 /dev/fd1 \device\floppy1
... ...
/dev/fd15 /dev/fd15
/dev/sr0 \device\cdrom0 /dev/sr0 \device\cdrom0
/dev/sr1 \device\cdrom1 /dev/sr1 \device\cdrom1
... ...
/dev/sr15 /dev/sr15
/dev/scd0 \device\cdrom0 /dev/scd0 \device\cdrom0
/dev/scd1 \device\cdrom1 /dev/scd1 \device\cdrom1
... ...
/dev/scd15 /dev/scd15
/dev/sda \device\harddisk0\partition0 (whole disk) /dev/sda \device\harddisk0\partition0 (whole disk)
/dev/sda1 \device\harddisk0\partition1 (first partition) /dev/sda1 \device\harddisk0\partition1 (first partition)
... ...
/dev/sda15 \device\harddisk0\partition15 (fifteenth partition) /dev/sda15 \device\harddisk0\partition15 (fifteenth partition)
/dev/sdb \device\harddisk1\partition0 /dev/sdb \device\harddisk1\partition0
/dev/sdb1 \device\harddisk1\partition1 /dev/sdb1 \device\harddisk1\partition1
[up to] [up to]
/dev/sddx \device\harddisk127\partition0 /dev/sddx \device\harddisk127\partition0
/dev/sddx1 \device\harddisk127\partition1 /dev/sddx1 \device\harddisk127\partition1
... ...
/dev/sddx15 \device\harddisk127\partition15 /dev/sddx15 \device\harddisk127\partition15
</screen> </screen>
<para> <para>